The present invention pertains to timber and log cutting devices, and, more particularly, pertains to a device having two adjustable cutting blades mounted on a traveling carriage for cutting horizontal sections from logs in successive back and forth passes.
The transformation of logs and raw timber into lumber, and thence into wood products that range from baseball bats and boxes, furniture and flooring, pencils, baskets, crates and pallets, comprises a number of steps from forest to sawmill and from sawmill to lumberyard, and thence to the manufacturing, chemical or paper plant or factory.
Even with modern equipment and machinery one of the most difficult steps in the logging process involves the transportation of the felled trees (logs) from the forest or woods to the sawmill. The lumbermen generally must skid the logs from the site where they have been cut to a landing (a central location in the woods or forest) for transportation to a sawmill usually by securing the logs to a log skidder that conveys the logs to the landing. The logs can also be placed on sleds, with the sleds then being attached to the log skidders for transport to the landing and thence to the sawmill. This necessitates the cutting of trails or roads through the woods or forest for connecting the logging site to the landing. Additional trails or roads may need to be cut for connecting the landing to a highway if the logs are of sufficient length and diameter that they require transport to the sawmill by a heavy duty log carrying tractor trailer.
In view of the above, it is advantageous to cut the logs into manageable pieces of lumber either on site or at the landing in order to facilitate the removal of the logs from the forest. However, this requires that some type of cutting or sawing unit, such as a band saw, be available for transport to the logging site or landing for performing the requisite log cutting. Thus, the cutting or sawing unit should be portable as logging sites are often located in rugged terrain and remote areas. Such a cutting or sawing unit should also be adaptable for use at smaller sites such as wood lots that are usually located on a portion of a tract of farmland. The size of the cutting or sawing unit should preferably be such as to minimally disturb or disrupt the tract of farmland as the unit is being taken to the site for log cutting and removal therefrom when the log cutting is completed.
The present invention comprehends a bi-directional cutting band mill utilizing two saw blades for cutting sections from a log by consecutive reciprocable passes of the saw blades.
The band mill of the present invention includes a lower frame or spaced-apart guide rails for placement on the ground or that are part of a wheelable trailer assembly. Supported on the lower frame for reciprocable movement thereon is a carriage or framework. In the preferred embodiment the carriage moves over the log during the successive cutting operations on the log. The carriage includes stanchion members that ride upon the lower frame and that are interconnected by cross members that support thereon the main saw blade motor and other structural elements that cooperate to raise, lower, and adjust both saw blades.
Mounted to the stanchion members and spanning the lower frame is a pair of spaced-apart band saws with the teeth of each band saw generally facing inward toward each other. The band saws are driven by the main saw drive motor and an interconnected pulley and belt system including a drive pulley and main drive belt and ancillary band saw belts and pulleys.
The band saws are capable of being simultaneously raised and lowered as a unit so that they can be lifted completely above the log, and the band saws are also capable of selective incremental adjustment for cutting through the log at the desired depth. In order to simultaneously lift both band saws the band saws are interconnected to each other by a pair of lift bars. Each lift bar is pivotally mounted to a guide, and each guide is slidably mounted to the stanchion members so that when both guides slide upward on the respective stanchion members by a lift motor and chain arrangement, the coincident raising of both band saws occurs and when the guides slide downward on the respective stanchion members the coincident lowering of both band saws results.
In addition, the band saws are capable of individual selective incremental adjustment to obtain the desired depth of cut through the log. A manually operable rack and pinion arrangement permits the operator to position in turn each band saw adjacent the end of the log for the desired depth of cut while simultaneously lifting the other band saw above the log so the cut can be made. As successive sections of the log are cut one band saw is utilized for the cutting while the other band saw is positioned above the log and passes over the log. After the cut is completed the positions of the band saws are changed for the next pass, in the reverse direction, by the band saws for making the next cut.
It is an object of the present invention to provide a band mill that employs two band saws for cutting logs in both directions of travel in order to reduce unnecessary cutting motion and increase productivity in cutting successive sections of the log.
It is another object of the present invention to provide a band mill capable of cutting logs in back and forth passes that utilizes the less expensive type of band saw that has teeth on only one side as opposed to the more expensive saw blades that have teeth on both sides.
It is still another object of the present invention to provide a band mill for bi-directional cutting wherein one saw blade is turned inside out prior to mounting on the carriage so that the teeth on both band saws are on opposite sides thus allowing the band mill to cut logs in both directions of travel.
Yet another object of the present invention is to provide a band mill wherein the sawdust produced during the back and forth cutting movements is discharged in the same direction by both blades.
Yet still another object of the present invention is to provide a band mill that uses the same power source and drive elements for making log cuts in both directions of travel of the carriage and the band saws.